1. Field of the Invention
The field of art to which this invention pertains includes multiple element planetary gear mechanisms and more specifically planetary wheel ends.
2. Description of the Prior Art
The use of drive axles with planetary outer ends is well known in such heavy duty applications as costruction machinery and mining equipment. Planetary wheel ends have a multiplicity of members including a plurality of generally equiangularly disposed planetary pinions journalled in an appropriate carrier or carrier assembly. One known design utilizes an axle drive shaft to rotate a sun gear that meshes with this plurality of planet pinions which in turn react against a stationary internal ring gear, thereby causing the carrier assembly to rotate and thus become the planetary output member.
Generally, the planet carrier takes the form of a planet carrier assembly made up of several parts in order to permit the ready assembly and journalling of the planet pinions relative to the carrier assembly. One known design of this type utilizes a planet carrier housing having a plurality of boss portions that serve as mounting and locating areas for a planet carrier plate that is generally rigidly bolted to the former. The planet carrier housing and the planet carrier plate include concentric bores for retaining bearing assemblies that are used for journalling the planet pinions.
In heavy duty applications of this type, very high torque loads are transferred through the planetary assemblies, with this torque transfer tending to introduce a circumferential bending moment via the attempted rotation of the planet carrier plate relative to the planet carrier. However, even a small amount of circumferential twist between the carrier housing and the carrier plate will tend to effect the necessary bearing clearances, thereby drastically reducing the bearing service life. The use of cap screws for bolting together the carrier plate and carrier housing will reduce this undesired bending moment, but can, however, subject the cap screws to undesirable shear loads that will adversely affect their service life.